Tektronix TCP202 User manual

Instruction Manual

TCP202

15 Ampere AC/DC Current Probe

070-9542-00

Tektronix products are covered by U.S. and foreign patents, issued and

pending. Information in this publication supercedes that in all previously

published material. Specifications and price change privileges reserved.

Printed in the U.S.A.

Tektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000

TEKTRONIX, TEK, and TekProbe are registered trademarks of Tektronix, Inc.

WARRANTY

Tektronix warrants that the products that it manufactures and sells will be free from defects

in materials and workmanship for a period of one (1) year from the date of purchase from

an authorized Tektronix distributor. If any such product proves defective during this

warranty period, Tektronix, at its option, either will repair the defective product without

charge for parts and labor, or will provide a replacement in exchange for the defective

product. Batteries are excluded from this warranty.

In order to obtain service under this warranty, Customer must notify Tektronix of the defect

before the expiration of the warranty period and make suitable arrangements for the

performance of service. Customer shall be responsible for packaging and shipping the

defective product to the service center designated by Tektronix, shipping charges prepaid,

and with a copy of customer proof of purchase. Tektronix shall pay for the return of the

product to Customer if the shipment is to a location within the country in which the

Tektronix service center is located. Customer shall be responsible for paying all shipping

charges, duties, taxes, and any other charges for products returned to any other locations.

This warranty shall not apply to any defect, failure or damage caused by improper use or

improper or inadequate maintenance and care. Tektronix shall not be obligated to furnish

service under this warranty a) to repair damage resulting from attempts by personnel other

than Tektronix representatives to install, repair or service the product; b) to repair damage

resulting from improper use or connection to incompatible equipment; c) to repair any

damage or malfunction caused by the use of non-Tektronix supplies; or d) to service a

product that has been modified or integrated with other products when the effect of such

modification or integration increases the time or difficulty of servicing the product.

THIS WARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THE

LISTED PRODUCTS IN LIEU OF ANY OTHER WARRANTIES, EXPRESS OR

IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED

WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR

PURPOSE. TEKTRONIX’ RESPONSIBILITY TO REPAIR OR REPLACE

DEFECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY

PROVIDED TO THE CUSTOMER FOR BREACH OF THIS WARRANTY.

TEKTRONIX AND ITS VENDORS WILL NOT BE LIABLE FOR ANY

INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES

IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR HAS

ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.

TCP202 Instruction Manual

i

Table of Contents

General Safety Summary iii. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Getting Started 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Features and Accessories 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Installation 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Compensating the Probe (Optional) 4. . . . . . . . . . . . . . . . . . . . .

Operating Basics 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Measurement Limits 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Degaussing and Balancing the Probe 6. . . . . . . . . . . . . . . . . . . .

Measurement Procedures and Techniques 7. . . . . . . . . . . . . . . . .

Reference 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Power Measurements 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Inductance Measurements 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Continuity Test of Multiple-Conductor Cable 18. . . . . . . . . . . . . .

Measuring Inductor Turns Count 18. . . . . . . . . . . . . . . . . . . . . . . .

Specifications 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Warranted Characteristics 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Typical Characteristics 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Nominal Characteristics 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Maintenance 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cleaning the Probe Head 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Servicing the Compensation Box 30. . . . . . . . . . . . . . . . . . . . . . .

Probe Head Disassembly 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Obtaining Replacement Parts 38. . . . . . . . . . . . . . . . . . . . . . . . . .

Preparation for Shipment 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Performance Verification and Adjustment 40. . . . . . . . . . . . . .

Test Procedure Conditions 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Equipment Required 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DC Accuracy 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Bandwidth 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Rise Time 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Calibrator Accuracy (Optional) 43. . . . . . . . . . . . . . . . . . . . . . . . .

Replaceable Parts 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contents

ii

TCP202 Instruction Manual

List of Figures

Figure 1: TCP202 Current Probe 1. . . . . . . . . . . . . . . . . . . . . . . .

Figure 2: Coarse Balance Adjustment 3. . . . . . . . . . . . . . . . . . . .

Figure 3: Connecting the Calibrator 4. . . . . . . . . . . . . . . . . . . . .

Figure 4: Polarity of Current Flow 8. . . . . . . . . . . . . . . . . . . . . .

Figure 5: Measuring Differential Current and Nulls 9. . . . . . . . .

Figure 6: Increasing the DC Measurement Range 11. . . . . . . . . . .

Figure 7: Increasing Probe Sensitivity 12. . . . . . . . . . . . . . . . . . . .

Figure 8: Measuring Inductance with a Low-Impedance

Source 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 9: Linear Current versus Time Ramp 16. . . . . . . . . . . . . . .

Figure 10: Measuring Inductance with a High-Impedance

Source 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 11: High-Impedance Source Current Ramp 17. . . . . . . . . .

Figure 12: Measuring the Number of Turns in a Coil 19. . . . . . . .

Figure 13: Turns Measurement Using Reference Coil 19. . . . . . .

Figure 14: Frequency Derating 23. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 15: Insertion Impedance – Magnitude –

Single Conductor 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 16: Insertion Impedance – Phase Angle –

Single Conductor 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 17: Insertion Impedance – Magnitude –

10-Turn #24 AWG Primary 25. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 18: Insertion Impedance – Phase Angle –

10-Turn #24 AWG Primary 26. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 19: Current Ratings 27. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 20: Replacing TekProbe Interface Pins 30. . . . . . . . . . . . .

Figure 21: Replacing the TekProbe collar 31. . . . . . . . . . . . . . . . .

Figure 22: Removing the Compensation Box Covers 32. . . . . . . .

Figure 23: Accessing the Gain Adjustment 33. . . . . . . . . . . . . . . .

Figure 24: Replacing the Compensation Box Cover 34. . . . . . . . .

Figure 25: Removing the Strain Relief Boot 35. . . . . . . . . . . . . . .

Figure 26: Removing the Top Half of the Probe 36. . . . . . . . . . . .

Figure 27: Removing the Probe Slide 37. . . . . . . . . . . . . . . . . . . .

Figure 28: Removing the Current Transformer 38. . . . . . . . . . . . .

Figure 29: TCP202 and Replaceable Accessories 46. . . . . . . . . . .

Figure 30: Replaceable Parts – Compensation Box 48. . . . . . . . .

Figure 31: TCP202 Optional Accessories 50. . . . . . . . . . . . . . . . .

TCP202 Instruction Manual

iii

General Safety Summary

Review the following safety precautions to avoid injury and prevent

damage to this product or any products connected to it.

Injury Precautions

Do Not Operate in Wet/Damp Conditions. To avoid electric shock, do not

operate this product in wet or damp conditions.

Do Not Operate in an Explosive Atmosphere. To avoid injury or fire

hazard, do not operate this product in an explosive atmosphere.

Observe Maximum Working Voltage. Do not use this product on bare

wires above 300 V (DC + peak AC).

Product Damage Precautions

Do Not Drop the Probe Head. The probe head contains fragile

components that can be damaged by a high impact. Take care to

prevent the probe head from dropping on the floor or other hard

surface. Secure the probe head in a safe location when not in use.

Do Not Operate With Suspected Failures. If you suspect there is damage

to this product, have it inspected by qualified service personnel.

Do Not Immerse in Liquids. Clean the probe using only a damp cloth.

Refer to cleaning instructions.

Safety Terms and Symbols

Terms in This Manual. These terms may appear in this manual:

WARNING. Warning statements identify conditions or practices that

could result in injury or loss of life.

CAUTION. Caution statements identify conditions or practices that

could result in damage to this product or other property.

General Safety Summary

iv

TCP202 Instruction Manual

Terms on the Product. These terms may appear on the product:

DANGER indicates an injury hazard immediately accessible as you

read the marking.

WARNING indicates an injury hazard not immediately accessible as

you read the marking.

CAUTION indicates a hazard to property including the product.

Symbols on the Product. These symbols may appear on the product:

Protective Ground

(Earth) Terminal

ATTENTION

Refer to Manual

Double

Insulated

DANGER

High Voltage

Certifications and Compliances

Refer to the specifications section for a listing of certifications and

compliances that apply to this product.

TCP202 Instruction Manual

1

Getting Started

This section describes the TCP202 Current Probe and gives

instructions on how to install and functionally test the probe.

Features and Accessories

The TCP202 Current Probe (Figure 1) is a 50 MHz current probe for

use with Tektronix oscilloscopes that have the TekProbe interface.

The probe can measure up to 15 A (DC + peak AC).

Figure 1: TCP202 Current Probe

Getting Started

2

TCP202 Instruction Manual

Probe Head. The probe head contains a Hall Effect

device for measuring current. The jaw of the probe

clamps on any wire (including insulation) that is less

than or equal to 3.8 mm (0.15 inches) in diameter.

TekProbe Interface. The TekProbe interface provides

power, signal, and probe characteristic data.

If your oscilloscope does not support the TekProbe

interface, you can use the optional 1103 probe power

supply as an effective interface. Contact your local

Tektronix representative for more information.

Degauss. The degauss button removes residual

magnetism from the probe core that would otherwise

cause measurement errors.

Balance Thumbwheel. The balance thumbwheel

compensates for minor DC offsets of the probe output.

Coarse Balance Adjustment. The coarse balance

adjustment centers the range of the balance thumb-

wheel. Use this adjustment only if the thumbwheel

does not have enough range.

Calibrator (optional). With some TDS oscilloscopes, you

can compensate the probe for maximum accuracy using

the optional calibrator. Use the calibrator only if your

oscilloscope displays the A symbol when the current

probe is connected. (For ordering information, see

Replaceable Parts starting on page 44.)

Getting Started

TCP202 Instruction Manual

3

Installation

Install the TCP202 Current Probe as follows:

1. Set the input channel to a zero reference point.

2. Connect the output of the probe to the TekProbe interface of the

oscilloscope or other measurement instrument. The measurement

instrument input must have a ground reference.

If your TDS oscilloscope does not display amperes/division, interpret

volts/division as amperes/division.

If you are using the 1103 TekProbe Power Supply, you must set the

oscilloscope input coupling to DC and the input impedance to 50 

Interpret V/division as 10 A/division. For example, interpret

100 mV/division as 1 A/division.

3. With the probe jaw empty, push the slide on the probe until it

locks in the CLOSED position.

4. Press the DEGAUSS button.

5. Balance the probe as follows:

a. Set the oscilloscope vertical scale to 10 mA/division.

b. Open and close the probe jaw.

c. Adjust the BALANCE thumbwheel until the displayed

signal is zero.

6. If you cannot zero the display as described in step 5c, use the

coarse balance adjustment (Figure 2) to center the range of the

thumbwheel.

Coarse balance

Figure 2: Coarse Balance Adjustment

Getting Started

4

TCP202 Instruction Manual

Compensating the Probe (Optional)

With some TDS oscilloscopes, you can compensate the probe for

maximum accuracy using the optional calibrator. Perform this

procedure only if your oscilloscope displays the A symbol when

you connect the probe output to the oscilloscope input.

1. To connect the calibrator, press the release button (Figure 3) and

connect the calibrator to the probe compensation output of the

oscilloscope.

Release button

Figure 3: Connecting the Calibrator

2. Close and lock the probe jaw over the calibrator loop.

3. Adjust the oscilloscope to display the signal.

4. Press VERTICAL MENUCal ProbeOK Compensate Gain.

If the probe passes the compensation routine, the probe is accurate to

within ± 1% from 50 mA to 5 A and ± 2% from 5 A to 15 A.

If the probe fails the compensation routine, refer to the procedure for

checking the DC accuracy of the probe on page 41 and the procedure

for accessing the internal gain adjustment on page 32.

Repeat this procedure whenever you move the current probe to

another input.

TCP202 Instruction Manual

5

Operating Basics

This section contains important precautions and techniques for

clamping the probe on a circuit and taking basic measurements.

Measurement Limits

Before you clamp the probe on a circuit to measure current, observe

the precautions for uninsulated wires and the maximum current

ratings.

Precautions for Uninsulated Conductors

WARNING. To avoid electrical shock from uninsulated conductors,

observe the following precautions:

Disconnect the power to the uninsulated conductor before inserting

the conductor in or removing the conductor from the probe jaw.

Do not apply a voltage higher than 300 V (DC + peak AC) between

earth ground and an uninsulated conductor that is in the probe jaw.

Maximum Current Rating

There are two basic current ratings: maximum peak current and

maximum continuous current. In addition, the maximum peak

current is limited by the A/second rating. For a graph of these limits,

refer to Figure 19 on page 27.

The maximum peak current is 50 A with a pulse width ≤ 10 ms

(500 mAseconds). This 500 mAseconds rating applies to any peak

current over 15 A. The product of the peak current and pulse width

(at 50% of peak) must be 500 mAseconds or less. For example, the

maximum pulse width is 20 ms for a pulse of 25 A peak.

Operating Basics

6

TCP202 Instruction Manual

The maximum continuous current that this probe can measure is

15 A (DC + peak AC). This limit derates with frequency; as the

frequency increases, the maximum current rating decreases. For a

graph of this relationship, see Figure 14 on page 23.

Multiple Current Probes

Up to four TCP202 current probes may be used simultaneously on

one TDS Series oscilloscope if the total in-phase current measured

by all of the probes does not exceed 40 amperes. Above 40 amperes,

the TekProbe interface may overload and cause measurement or

display errors.

When one or two TCP202 current probes are used on a TDS Series

oscilloscope, the ratings are as shown in Figure 19 on page 27.

Degaussing and Balancing the Probe

For accurate measurements, you must occasionally degauss and

balance the probe. Degaussing removes residual magnetization from

the probe core that would otherwise shift the zero point and cause

measurement errors. Balancing the probe compensates for any DC

offset that remains on the probe output after degaussing.

Degauss and balance your probe in each of the following cases:

H After turning on the oscilloscope and allowing a 20-minute

warm-up period

H Whenever an overload condition occurs

H Whenever the probe is subjected to a strong external magnetic

field

H Whenever there is a measurable DC offset that does not come

from the conductor under test

To degauss and balance the probe, follow the installation procedure

on page 3.

You may degauss the probe with a conductor in the jaw if you first

disconnect the power to the conductor. This technique compensates

for any offsets caused by stray DC magnetic fields around the circuit

under test.

Operating Basics

TCP202 Instruction Manual

7

CAUTION. While degauss occurs, the probe will induce a small

voltage in the unpowered circuit (33 mV in series with 1.5 M). Your

circuit must be able to absorb this induced voltage. With low

impedance circuits, several amperes may be induced in the circuit

being measured. This may be of concern if you are using very small

conductors.

Measurement Procedures and Techniques

This section presents procedures and techniques for basic current

measurements.

Basic Procedure

Measure AC or DC current in a single conductor as follows:

1. Observe the safety precautions and operating limits.

2. If necessary, degauss and balance the probe.

3. Close and lock the probe jaw over the conductor. Conventional

current flows from positive to negative. For the correct polarity

reading, connect the probe so that the current flow, from positive

to negative, is aligned with the arrow on the probe jaw (see

Figure 4).

4. Read the measurement. Adjust the display of the measurement

instrument as necessary.

5. If necessary, adjust the oscilloscope offset control to offset a DC

level. (AC coupling is automatically disabled on TDS oscillo-

scopes when the probe is connected.)

Operating Basics

8

TCP202 Instruction Manual

Figure 4: Polarity of Current Flow

Measuring Differential Current

You can place two conductors in a current probe to provide a

differential or null current measurement. This avoids the necessity of

using two current measurement systems with a differential

oscilloscope amplifier.

1. Orient the two conductors under test so that the polarities oppose

each other. Clamp the current probe around the two conductors as

shown in Figure 5.

2. Measure the current. A waveform above the baseline indicates

the conductor with the conventional current flow in the direction

of the probe arrow is carrying the greater current.

3. To adjust for a current null, adjust the current in one of the

conductors until the displayed measurement is zero.

Operating Basics

TCP202 Instruction Manual

9

Conductor 2

Current probe

Conductor 1

Current

Figure 5: Measuring Differential Current and Nulls

Operating Basics

10

TCP202 Instruction Manual

Extending the DC Current Range

You may encounter situations where your measurement exceeds the

maximum current rating of the connected probe. This section

discusses methods for extending DC current ranges without

exceeding specified limits.

WARNING. To avoid personal injury or equipment damage, do not

exceed the specified electrical limits of the oscilloscope or any

applicable accessories. When using multiple conductors, do not

exceed current limits on either conductor.

If you want to measure a low-amplitude AC component that is

superimposed on an extremely large steady state DC component

(such as in a power supply), or if you want to extend the DC current

range of your probe, you can add offset (bucking) current with a

second conductor.

By adding bucking current, the amount of DC current that you

measure is the difference between the DC component of the signal

and the bucking current. You can then calculate the amount of DC

current in the conductor under test by adding the value of the

measured current to the value of the bucking current.

To supply additional bucking current, place a second conductor that

has a pure DC component of known value in the probe jaw with the

conductor under test, as shown in Figure 6(a) on page 11. Orient the

second conductor so that the bucking current flows in the opposite

direction of the DC flow in the conductor under test.

You can increase the value of the bucking current by winding

multiple turns of the second conductor around the probe, as shown in

Figure 6(b) on page 11. The bucking current is equal to the current

flowing in the conductor, multiplied by the number of turns wound

around the probe. For example, if the second conductor has a current

of 100 mA DC and is wrapped around the probe five times, the DC

bucking current is 100 mA multiplied by 5, or 500 mA DC.

Operating Basics

TCP202 Instruction Manual

11

NOTE. Adding a second conductor to the probe reduces the upper

bandwidth limit of the probe.

Conductor

under test

Second conductor

suppling bucking

current

Extra turns added

to increase

bucking current

Conductor

under test

Current

(a) Adding a second conductor

(b) Adding multiple turns

Current

Current probe

Figure 6: Increasing the DC Measurement Range

Operating Basics

12

TCP202 Instruction Manual

Increasing Measurement Sensitivity

If you are measuring DC or low-frequency AC signals of very small

amplitudes, you can increase measurement sensitivity of your

Current Probe by winding several turns of the conductor under test

around the probe as shown in Figure 7. The signal is multiplied by

the number of turns around the probe.

When viewing the signal on the oscilloscope screen, divide the

displayed amplitude by the number of turns to obtain the actual

current value. For example, if a conductor is wrapped around the

probe five times and the oscilloscope shows a reading of 50 mA DC,

the actual current flow is 50 mA divided by 5, or 10 mA DC.

NOTE. Winding multiple turns around the probe increases the

insertion impedance of the probe which can affect the accuracy of

your measurements and the circuit under test. For graphs of insertion

impedance, refer to figures 15 and 17 on page 23.

Extra turns for

increased sensitivity

Conductor

under test

Current probe

Figure 7: Increasing Probe Sensitivity

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Tektronix TCP202 User manual

Tektronix TCP202 User manual

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